A downhole moineau pump assembly used on a producing oil well consists of a stator, a rotor that extends through the stator, and a surface mounted top drive unit that rotates the rotor. The rotor and stator sealingly engage each other at spaced intervals to form a series of annular spaces. As the rotor rotates, fluids are drawn through an inlet and up the series of annular spaces between the rotor and the stator.
In oil wells with high solids content, the downhole moineau pump assembly periodically ceases to function due to a build up of solids blocking the inlet.